The 2015 Digital Fabrication Lab project, TOCA (Tool Operated Choreographed Architecture) explored the potentials of human-machine collaboration in a manner that expanded on the knowledge acquired in the 2014 STIK Pavilion project. The research and development of the TOCA project sought to utilize the adaptability and creativity of humans, and combine it with the precision and efficiency of machinery. The resulting pavilion utilized a scanning and guiding system to support human users on-site, a material used to extrude components (foam), a handheld “smart” tool to dispense the material, and a geometric form which iteratively optimized through use of a feedback system that integrated human error. The pavilion project, which began with a digitally-defined target model, was constructed on-site by teams of users, who sprayed components by hand. The results of the work were scanned and analyzed, and an updated digital model was defined and indicated to users for the next layer of the project. In this manner, any “errors” introduced throughout the spraying process were integrated into subsequent construction steps. The final pavilion represents the accumulation and integration of these errors. The project was made possible through cross-disciplinary collaboration; structural engineering, architecture, and computer science laboratories contributed to realizing the technologies and the final output.